This tutorial shows how to easily make a sword in Curvy, but you will also learn how to make one model take on the shape of another using Image Apply which happens to be an excellent technique for getting tricky shapes into Secold Life as Sculpted Prims.

Here is the sequence of images I will be stepping through in the tute:

Inflate Image

There are two methods of converting images into meshes in Curvy - Auto and Relief.
Images (1) and (2) show the auto method. A white sword is created from the outline between black and white on the image. N.B. I turned off 'Smooth' to create an inflated mesh with sharp lines. This method is quick and easy.
Images (3) and (4) show the relief method. I used spline shapes and a tween to create a smooth gradient inside the sword - but any greyscale image or effect will work. N.B. the purple background is to help you see the shape - in the actual image I used the background is pure black - and any pure black parts of the image are empty holes in the inflate mesh.
The relief method has created a scooped out curve on the blade which I think suits the fantasy look well - although it is slightly harder to make the base image (1 min if you know how to do it!).

Smooth press S

Once inflated the surface might be a bit rough - using a higher res input image will help - I used a 2048 height image. To get rid of any remainign roughness select the mesh and press S. The sword is smoothed in (5)

Scale holding Z to scale along axis.

The scale is likely to be wrong after inflate - now you could change the scale parameter in the inflate dialog, but it is easier to scale by hand afterwards. Hold down the Z key while using the scale tool to resize the mesh. In this example I left the sword more box shaped than flat to help with the next step -I knew I could always scale the sword flat later in SL.

Draw lathe inside sword

Now we get to the first step of the Apply process. The aim here is to make a regular Lathe object (which is perfect for sculptie export) match the shape of our inflated blade (which has the wrong UVs to be a sculptie). This is achieved by growing the surface of a Lathe to fit the sword's surface. To start with the lathe must sit entirely inside the sword.
Draw a Lathe inside the sword - image (5) shows the kind of lathe you need - but yours should be completely hidden by the sword's surface. It helps to set the lathe's diffuse colour to bright red to spot any overlap.

Add a white 512 res image to Curvy map or flood fill 512 res default grey image with white and increase Curvy map displacement until it covers the sword. Image (6) shows the surface of the lathe being pushed out by the white curvy map, and covering the sword underneath. Once it covers - flood the map with grey again ready for the next step.

Apply children - addIn the groups panel drag the sword onto the lathe to add it as a child. Then use "Image/Apply Children: Add". Select the original sword and press H to hide it. You should now have a replica as in image (7).

Export Sculptie

Check you have Sculptie Mode turned on, and export sculpties from the File Menu. Here is my sword blade uploaded to SL with a metalic sheen.

Last edited by Simon on Thu May 06, 2010 9:35 pm, edited 1 time in total.

I've had some questions about this technique - and so everyone can benefit from the answers I'll answer here

- why first you make a shape into and after out. First you need to understand "Curvy Maps" - these are like displacement maps but work in Real-Time instead of at render time. White parts of this map push the surface out. Black parts push it in.
The aim is to make a Curvy map that turns the simple smooth Lathe into the more complicated sword mesh. The reason for this is that the smooth Lathe will export as a perfect sculptie, while the original sword would not export well.
So, setting the Curvy map to grey and then to white, makes sure the Curvy map has enough range to cover all the necessary displacement. If there is not enough range then the far bits of the sword would not be filled out.

- do the shape have to be really precise (like the mesh ?) It is more important that the inner shape is smooth. If it fits quite close to the sword you will get a slightly better result, but it does not have to fit all the corners and details.
That said, it also helps if the inner shape has a resolution of over 20,000

- in this case, why can't we just make a lathe circle around the mesh directly which covers the mesh totally ? When you use "Apply: Add" it pushes the surface out until it hits a child object. If the lathe already was outside the sword Apply would not hit the sword as it pushed out and the technique would fail.

- for {a complex shape}, do I have to draw a lathe which is completely like the {shape}? It is worth doing some experiments here - if your shape is concave eg: a 'U' shape, your lathe will also need to follow the 'U' shape, but smoothly without details. For an 'X' shape you could just draw a sphere in the middle and the arms could be made by the Curvy Map.

Last question, do you have an affiliate program to sell your soft to other Second life residents ?You can signup as a ShareIt affiliate and register to sell Curvy. Then when you give out a link to Curvy with your affiliate ID in you will get part of the price if the person eventually buys Curvy.